Multifrequency electron paramagnetic resonance (EPR) of spin-labeled protein is a powerful spectroscopic technique to study protein dynamics on the rotational correlation time scale from 100 ps to 100 ns. Nitroxide spin probe, attached to cysteine residue, reports on local topology within the labeling site, dynamics of protein domains reorientation, and protein global tumbling in solution. Due to spin probe's magnetic tensors anisotropy, its mobility is directly reflected by the EPR lineshape. The multifrequency approach significantly decreases ambiguity of EPR spectra interpretation. The approach, described in this chapter, provides a practical guideline that can be followed to carry out the experiments and data analysis.